Rust Platform

In the previous exercise, you used match to handle Option. But matching every time gets verbose:

let name: Option<String> = get_name();
let upper = match name {
    Some(n) => Some(n.to_uppercase()),
    None => None,
};

Rust provides combinators — methods that transform Options without explicit matching.

.map() — transform the inner value

let name: Option<String> = Some("alice".to_string());
let upper = name.map(|n| n.to_uppercase());
// Some("ALICE")

let empty: Option<String> = None;
let upper = empty.map(|n| n.to_uppercase());
// None — closure never runs

In Python, this is like: x.upper() if x is not None else None

.unwrap_or() — provide a default

let count: Option<i32> = None;
let value = count.unwrap_or(0);  // 0

let count: Option<i32> = Some(42);
let value = count.unwrap_or(0);  // 42

.unwrap_or_else() — lazy default

When computing the default is expensive, use a closure:

let value = count.unwrap_or_else(|| expensive_computation());

.and_then() — chain Option-returning functions

When your …